In wire line operations, wire line retrieval and installation tools are commonly used. Most items which are installed in a tubing string are equipped with API standard fishing necks. A standard fishing neck normally includes an undercut shoulder to enable grappling by installation or retrieval tool. Quite often the API standard fishing neck will wear away so that only a stub pipe without an undercut shoulder is left. Retrieval of this sort of device is implemented by an overshot such as that manufactured by Bowen. A common drawback in the installation and retrieval tools of the past is the inability of the operator to undo the connection achieved by the tool. For instance, a wire line equipped with a Bowen overshot can be used to grasp a device installed in a tubing string in a fishing job. However, the device to be retrieved may sometimes stick and the wire line operator is unable to retrieve it on the wire line. A substantially heavier wire line may be required. The Bowen overshot is difficult to disconnect from the stub which it has engaged. Occasionally disconnection can be achieved by substantial jarring which will sometimes shear a pin. Reconstruction and reassembly of the tool at the surface is then required to repair the harm done by this step. Retrieving tools other than the named model suffer similar infirmities. Once they latch onto an item to be pulled or retrieved, substantial problems exist in selective downhole disconnection. Should a fishing job utilizing a certain weight of fishing equipment begin, it is almost impossible to disconnect the apparatus from the fish and substitute heavier equipment. As a consequence, retrieval of the fishing equipment itself compounds the problem.
The apparatus of the present invention is particularly adapted to overcome these difficulties. It can be used in a fishing job with various adaptors on the lower end to enable it to enable an API standard fishing neck, a worn fishing neck which then resembles a stub member, or an inside grappling job. In all these adaptations, the upper portion of the tool remain the same. The upper portion of the tool is able to be latched or actuated on a first jar. Should it be impossible to retrieve the fish in question, a second jar will release the fish so that the tool can be retrieved and a heavier gauge device be used.